MarioAriasC

<dependency>
    <groupId>org.funktionale</groupId>
    <artifactId>funktionale-composition</artifactId>
    <version>1.1</version>
</dependency>

MarioAriasC

<repository>
    <id>central</id>
    <name>bintray</name>
    <url>http://jcenter.bintray.com</url>
</repository>

MarioAriasC

data class Item(val name: String, val price: Double, val discount: Double, val quantity: Double)

object ItemDao {
	fun findItemsForInvoice(invoiceId: Int): List<Item> {
		return listOf(
			Item("Item A", 10.0, 0.0, 1.0),
			Item("Item B", 100.0, 0.0, 1.0),
			Item("Item C", 50.0, 10.0, 3.0),
			Item("Item D", 45.0, 0.0, 1.5),
			Item("Item E", 8.5, 5.0, 20.0),

MarioAriasC

val items = ItemDao.findItemsForInvoice(1)
	
val total = items
	.map { (_, itemPrice, discount, quantity) -> itemPrice * quantity to discount }
	.map { (price, discount) -> price to discount / 100.0 }
	.map { (price, discPercentage) -> price - (price * discPercentage) }
	.sum()

MarioAriasC

val extract: (Item) -> Pair<Double, Double> = { (_, itemPrice, discount, quantity) -> itemPrice * quantity to discount }
val discount: (Pair<Double, Double>) -> Pair<Double, Double> = { (price, discount) -> price to discount / 100.0 }
val price: (Pair<Double, Double>) -> Double = { (price, discPercentage) -> price - (price * discPercentage) }

MarioAriasC

val total = items
	.map(extract)
	.map(discount)
	.map(price)
	.sum()

MarioAriasC

val total = items
	.map(extract andThen discount andThen price)
	.sum()

MarioAriasC

fun underline(it: String) = "_${it}_"
fun background(it: String) = "\u001B[41m$it\u001B[0m"

MarioAriasC

println((::underline forwardCompose ::background)("Hello"))
println((::underline compose ::background)("Hello"))

MarioAriasC

import rx.Observable
import rx.Subscription
import rx.util.functions.Action1

/**
 * Created by IntelliJ IDEA.
 * @author Mario Arias
 * Date: 9/05/13
 * Time: 21:11
 */